This invention relates in general to welding machines and in particular to a new and useful device for sensing the travel speed of automatic welding machines and to a method of effecting the measurement.
The travel speed of the welding head of automatic welding machines depends on a number of parameters, such as the thickness of the welding seam to be produced, the welded and filler material, the welding electrode, and the voltage and current used. As a rule, however, the travel speed of the welding head is to be constant during the process of producing the welding seam. With straight-line welding seams, no difficulties arise, since a constant travel speed can be adjusted on the automatic welding machine.
Automatic welding machines, however, are also employed for producing welding seams which do not follow a straight line, but a curve. If, for example, surfacing of circular areas is concerned, where the welding beads follow a spiral, or if a welding seam is produced by spirally superimposing beads so that upon every full revolution the ring thus formed has a larger diameter, then, with a constant travel speed of the welding head, the relative speed between the welding head and the welded work varies continuously. In such cases, attempts have been made to adjust the travel speed of the welding head manually from time to time. This however, necessarily produces very considerably irregularities and fluctuations in the speed of the welding head relative to the work, which cannot readily be detected.